A fuel cell is a device or system that generates electricity by an electrochemical reaction in which oxygen and hydrogen combine to form water. An electrolyte in the cell carries charged particles across a cathode to an anode. Catalysts are often employed to accelerate and improve the efficiency of the electrochemical reaction. Fuel cell devices are a viable source of alternative energy. These devices are generally more efficient and produce less pollution than conventional sources of power. The electricity produced by fuel cells can be used to power, for example, aeronautical systems, computer devices, automotive systems and cellular devices.
Typically, fuel cells are classified by the type of electrolyte used. Fuel cell devices also feature different materials depending on an application or specific power requirements. The variety of fuel cells includes, for example, phosphoric acid, proton exchange membrane, molten carbonate, alkaline and solid oxide devices. The solid oxide fuel cell (SOFC) provides an environmentally clean and versatile power source that can efficiently convert fossil fuels into electricity and heat.
An SOFC comprises a dense electrolyte that is positioned between porous electrodes, namely, the cathode and anode. The dense electrolyte can be a solid oxygen-ion conductor such as yttria-stabilized zirconia (YSZ). Moreover, the cathode and anode can be ceramic composites such as strontium doped lanthanum manganite-YSZ and nickel-YSZ oxide, respectively. SOFC devices can also be assembled into a planar stack in which several cells are arranged with interconnects separating each cell.
An obstacle to commercializing SOFC devices is the substantial cost associated with their manufacture. This cost is an order of magnitude higher than fabricating a comparable gas turbine. One reason for this disparity is that SOFC devices are manufactured by batch processes. Batch processes are used to slowly heat and fire the fuel cell structure to prevent the electrolyte and electrodes from distorting. A standard batch process can uniformly heat and fire an SOFC at a thermal rate of about 1° C. per minute. This rate can require several hours to sinter the electrolyte and electrode structures. The process can also require multiple thermal cycles to heat and cool the cell during fabrication. Thus, manufacturing a fuel cell by such processes is entirely inefficient and expensive. With the growing demand for fuel cells, there is a specific need for an efficient fabrication process that is inexpensive and does not require multiple thermal cycles.